Abstract

An ion chromatography exercise is described that uses a free Internet-based software package, Virtual Column 2, to simulate retention behavior and to optimize separation conditions. Virtual Column 2 permits the detailed study of retention behavior of inorganic anions on a Dionex AS11 column using isocratic hydroxide eluents and also on a Dionex AS4A–SC column using carbonate-bicarbonate eluents. Collection of retention data from Virtual Column 2 allows students to investigate the effects of variation in eluent composition on retention, to examine separation selectivity in ion chromatography, and to evaluate the performance of simple retention models. Because the retention data provided by the software are based on actual experimental measurements an accurate evaluation of these models is possible. Effects of peak shape on resolution are also studied and the software can be used to perform computer-assisted optimization of separation conditions. The entire exercise, including familiarization with the software, takes about four hours and can be adjusted to fit into a shorter time frame if necessary. The ability to scan retention data over a wide range of eluent composition opens up the possibility of a computerized selection of the optimal separation conditions. The major characteristics of retention behavior, peak-shape effects and pH effects evident in ion chromatography (IC) using common stationary phases and eluents are illustrated.